Alexander Khitun

Electric-field-induced spin wave generation using multiferroic magnetoelectric cells

In this work, we report on the demonstration of voltage-driven spin wave excitation, where spin waves are generated by multiferroic magnetoelectric (ME) cell transducers driven by an alternating voltage, rather than an electric current. A multiferroic element consisting of a magnetostrictive Ni film and a piezoelectric [Pb(Mg1/3Nb2/3)O3](1−x)–[PbTiO3]x substrate was used for this purpose. By applying an AC voltage to the piezoelectric, an oscillating electric field is created within the piezoelectric material, which results in an alternating strain-induced magnetic anisotropy in the magnetostrictive Ni layer. The resulting anisotropy-driven magnetization oscillations propagate in the form of spin waves along a 5u2009μm wide Ni/NiFe waveguide. Control experiments confirm the strain-mediated origin of the spin wave excitation. The voltage-driven spin wave excitation, demonstrated in this work, can potentially be used for low-dissipation spin wave-based logic and memory elements.

Multi-frequency magnonic logic circuits for parallel data processing

We describe and analyze magnonic logic circuits enabling parallel data processing on multiple frequencies. The circuits combine bi-stable (digital) input/output elements and an analog core. The data transmission and processing within the analog part is accomplished by the spin waves, where logic 0 and 1 are encoded into the phase of the propagating wave. The latter makes it possible to utilize a number of bit carrying waves on different frequencies for parallel data processing. The operation of the magnonic logic circuits is illustrated by numerical modeling. We also present the estimates on the potential functional throughput enhancement and compare it with scaled CMOS. The described multi-frequency approach offers a fundamental advantage over the transistor-based circuitry and may provide an extra dimension for the functional throughput enhancement. The shortcoming and potentials issues are also discussed.

Pattern recognition with magnonic holographic memory device

In this work, we present experimental data demonstrating the possibility of using magnonic holographic devices for pattern recognition. The prototype eight-terminal device consists of a magnetic matrix with micro-antennas placed on the periphery of the matrix to excite and detect spin waves. The principle of operation is based on the effect of spin wave interference, which is similar to the operation of optical holographic devices. Input information is encoded in the phases of the spin waves generated on the edges of the magnonic matrix, while the output corresponds to the amplitude of the inductive voltage produced by the interfering spin waves on the other side of the matrix. The level of the output voltage depends on the combination of the input phases as well as on the internal structure of the magnonic matrix. Experimental data collected for several magnonic matrixes show the unique output signatures in which maxima and minima correspond to specific input phase patterns. Potentially, magnonic holographic devices may provide a higher storage density compare to optical counterparts due to a shorter wavelength and compatibility with conventional electronic devices. The challenges and shortcoming of the magnonic holographic devices are also discussed.

Magnonic holographic devices for special type data processing

In this work, we consider the possibility of building magnetic analog logic devices utilizing spin wave interference for special task data processing. As an example, we consider a multi-terminal magnonic matrix switch comprising multiferroic elements and a two-dimensional grid of magnetic waveguides connected via four-terminal cross-junctions. The multiferroic elements are placed on the periphery of the switch and used as input/output ports for signal conversion among the electric and magnetic domains. Data processing is accomplished via the use of spin wave interference within the magnonic matrix. We present the results of numerical modeling illustrating device operation for pattern matching, finding the period of the data string, and image processing. We also present the results of numerical modeling showing the device capabilities as a magnetic holographic memory. Magnonic holographic devices are of great potential to complement the conventional general-type processors in special task data processing a...

Magnonic Holographic Memory

Collective oscillation of spins in magnetic lattice known as spin waves (magnons) possess relatively long coherence length at room temperature, which makes it possible to build submicrometer scale holographic devices similar to the devices developed in optics. In this paper, we present a prototype 2-bit magnonic holographic memory. The memory consists of the double-cross waveguide structure made of Y3Fe2(FeO4)3 with magnets placed on the top of waveguide junctions. Information is encoded in the orientation of the magnets, while the read-out is accomplished by the spin waves generated by the microantennas placed on the edges of the waveguides. The interference pattern produced by multiple spin waves makes it possible to build a unique holographic image of the magnetic structure and recognize the state of each magnet. The development of magnonic holographic devices opens a new horizon for building scalable holographic devices compatible with conventional electronic devices.

Spin wave functions nanofabric update

We provide a comprehensive progress update on the magnonic spin wave functions nanofabric. Spin wave propagation does not involve any physical movement of charge particles. Information is encoded in the phase of the wave and computation is based on the principle of superposition. This provides a fundamental advantage over conventional charge based electronics and opens new horizons for novel nano-scale architectures. The coupling mechanism between the spin and charge domain is enabled by the Magneto-Electric (ME) cells. Based on our experimental work we show that, an electric field of ∼1MV/m would be required to obtain 90 degree magnetization rotation. The paper also provides a methodology for estimating ME cell switching energy. In particular, we show that this energy can be as low as 10aJ. In addition, we discuss different topology options and circuit styles for 1-bit/2-bit magnonic adders. Our estimates on benefits vs. 45nm CMOS implementation show that, for a 1-bit adder, ∼40X reduction in area and ∼60X reduction in power is possible with the spin wave based implementation. For the 2-bit adder, results show that ∼33x area reduction and ∼40X reductions in power may be possible.

Magnonic Holographic Memory: From Proposal to Device

In this paper, we present recent developments in magnonic holographic memory devices exploiting spin waves for information transfer. The devices comprise a magnetic matrix and spin wave-generating/detecting elements placed on the edges of the waveguides. The matrix consists of a grid of magnetic waveguides connected via cross junctions. Magnetic memory elements are incorporated within the junction, while the read-in and read-out are accomplished by the spin waves propagating through the waveguides. We present the experimental data on spin-wave propagation through NiFe and yttrium iron garnet Y3Fe2(FeO4)3 (YIG) magnetic crosses. The obtained experimental data show prominent spin-wave signal modulation (up to 20 dB for NiFe and 35 dB for YIG) by the external magnetic field, where both the strength and the direction of the magnetic field define the transport between the cross arms. We also present the experimental data showing parallel read-out of two magnetic memory elements via spin-wave interference. The recognition between the four possible memory states is achieved via proper adjustment of the phases of the interfering spin waves. All experiments are done at room temperature. Magnonic holographic devices aim to combine the advantages of magnetic data storage with wave-based information transfer. We present estimates on the spin-wave holographic devices performance, including power consumption and functional throughput. According to the estimates, the magnonic holographic devices may provide data processing rates higher than 1 × 1018 b/cm2/s while consuming 0.15 mW. Technological challenges and fundamental physical limits of this approach are also discussed.

Spin wave nanofabric update

We provide a progress update on the spin wave nanofabric. The nanofabric comprises magneto-electric cells and spin wave buses serving for spin wave propagation. The magneto-electric cells are used as the input/output ports for information transfer between the charge and the spin domains, while information processing inside the nanofabric is via spin waves only. Information is encoded into the phase of the propagating spin wave, which makes it possible to utilize waveguides as passive logic elements and take the advantage of using wave superposition for data processing. This provides a fundamental advantage over the conventional transistor-based logic circuitry allowing for functional throughput enhancement and power consumption minimization at the same time. We present recent accomplishments in the magneto-electric element development and integration with spin wave buses. In particular, we show the excitation and detection of the spin waves via multiferroic elements. In addition, we present different approaches to magnonic logic circuit engineering and provide the comparison with CMOS by mapping the designs to 45nm NANGATE standard cell libraries. The estimates show more than 40X power reduction and 53X area reduction for magnonic circuits. These results illustrate the potential advantages over conventional charge based electronics that could be a route to beyond CMOS logic circuitry.

Magnonic interferometric switch for multi-valued logic circuits

We investigated a possible use of the magnonic interferometric switches in multi-valued logic circuits. The switch is a three-terminal device consisting of two spin channels where input, control, and output signals are spin waves. Signal modulation is achieved via the interference between the source and gate spin waves. We report experimental data on a micrometer scale prototype based on the Y3Fe2(FeO4)3 structure. The output characteristics are measured at different angles of the bias magnetic field. The On/Off ratio of the prototype exceeds 13u2009dB at room temperature. Experimental data are complemented by the theoretical analysis and the results of micro magnetic simulations showing spin wave propagation in a micrometer size magnetic junction. We also present the results of numerical modeling illustrating the operation of a nanometer-size switch consisting of just 20 spins in the source-drain channel. The utilization of spin wave interference as a switching mechanism makes it possible to build nanometer-...We investigated a possible use of the magnonic interferometric switches in multi-valued logic circuits. The switch is a three-terminal device consisting of two spin channels where input, control, and output signals are spin waves. Signal modulation is achieved via the interference between the source and gate spin waves. We report experimental data on a micrometer scale prototype based on the Y3Fe2(FeO4)3 structure. The output characteristics are measured at different angles of the bias magnetic field. The On/Off ratio of the prototype exceeds 13u2009dB at room temperature. Experimental data are complemented by the theoretical analysis and the results of micro magnetic simulations showing spin wave propagation in a micrometer size magnetic junction. We also present the results of numerical modeling illustrating the operation of a nanometer-size switch consisting of just 20 spins in the source-drain channel. The utilization of spin wave interference as a switching mechanism makes it possible to build nanometer-...

Biological cell positioning and spatially selective destruction via magnetic nanoparticles

We report a procedure on biological cells (erythrocytes) where magnetite (Fe3O4) nanoparticles have been used for micro-scale blood cell positioning and space selective destruction. The experiment was accomplished on the top of the microelectromagnet serving as a source of magnetic field and as a local heater at the same time. We observed the controlled motion and focusing of the blood cells dragged by the flow of magnetic nanoparticles. Furthermore, we found that the increase of the electric current through the microelectromagnet leads to the local cell haemolysis. The haemolysis is observed only in the vicinity (5-10 microns) of the current-carrying wires. The whole procedure takes less than 3u2009seconds. The obtained results provide a rich resource showing the dynamics of cell dragging by the magnetic nanoparticles and demonstrate the feasibility of using magnetic nanoparticles for cell positioning and surgery on the cellular level with micrometer-scale precision.